An amplifier is an important device in a communications system. Due to a saturation feature of the amplifier, even for a linear amplifier, non-linear distortion may be generated at an output end. The non-linear distortion results in out-of-band radiation and in-band distortion, affecting performance of a transmitting device and a receiving device. Generally, a smaller peak-to-average power ratio (Peak to Average Power Ratio, PAPR for short) means a lower requirement on a linear working range of the amplifier. The PAPR is a ratio of a maximum power to an average power of signals.
802.11ad is a subsystem in the 802.11 series adopted by a wireless local area network (Wireless Local Area Network, WLAN for short), available at a 60 GHz band, and mainly used for transmission of wireless high-definition audio and video signals in a family, to provide a more complete high-definition video solution for family multimedia applications. Therefore, 802.11ad is also referred to as wireless gigabit (Wireless Gigabit, WiGig for short). One implementation solution of the 802.11ad technology is an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM for short) system. One OFDM symbol includes N subcarriers, and the N subcarriers include a guard subcarrier, a direct current subcarrier, a data subcarrier, and a pilot subcarrier. The data subcarrier is used to carry data, and the pilot subcarrier is mainly used for a receiving device to detect a phase deviation between a transmitting device and the receiving device. Because an OFDM symbol is an overlap of multiple subcarrier signals, a large PAPR may be generated if multiple subcarriers with identical or similar phases overlap at a moment. Therefore, it is critical for the OFDM system to reduce the PAPR.
In the prior art, a conventional partial transmit sequence (Partial Transmit Sequences, PTS for short) method is used to reduce the PAPR. Specifically, the N subcarriers in one OFDM symbol are divided into multiple subblocks, and subcarriers included in different subblocks are not the same. The transmitting device selects a corresponding phase rotation signal for each subblock, and the receiving device multiplies data received by each subblock by a phase rotation signal corresponding to the subblock to reduce the PAPR.
However, when the prior-art PTS method is used to reduce the PAPR, a dedicated data subcarrier needs to be occupied to transmit the phase rotation signal. This causes a waste of resources and results in a decrease in a throughput.